Halide ions water isotope effects

Unfortunately, no systematic studies of the water isotope effect on halide ion quadrupole relaxation have been performed. Wennerstrom... 

Table 6.3. Water Isotope Effect on the Shielding of Alkali and Halide Ions...

The finding by Craighead and Bryant [49S] of the same Cl relaxation rate for H2O and D2O solutions of NaClO is surprising in relation to possible models of the relaxation mechanism. We have reexamined this question and find, for a number of concentrations, an appreciably higher relaxation rate in D2O than in H2O (Table 9.1). The water isotope effect on relaxation is found to be 1.17 0.08 which is close to that found for halide ions and suggests, with the same... 

Schowen (1972) used the Swain-Bader theory to explain solvent kinetic isotope effects on SN2 reactions involving halides, in terms of the numer of water molecules solvating a halide ion in the transition state (assumed to be three) vs. the number solvating it in the bulk (four). The contribution of a single halide-water hydrogen bond was also taken to depend on the partial charge on the halide, which could be consistent with either theory. 

Carbon.— The use of isotopes in studies of the mechanisms of reactions of carbon dioxide or carbonates has been reviewed. Measurements using and give a rate constant of 1141 mol s" for the exchange reaction between carbon dioxide and carbonate ion at 25 °C the same techniques have been applied to the bovine carbonic anhydrase-catalysed exchange between carbon dioxide, its related species, and water.The decomposition rates of the alkyl monocarbonates in aqueous alkali and the effect of polyelectrolytes on the conversion of ammonium cyanate into urea have been reported. The application of calculations originally used for 5 b2 processes to the classical Sn2 halide ion-alkyl halide exchange reaction accounts quantitatively for the relative reactivities in terms of steric effects alone it is not necessary to invoke polar effects. Some further evidence for ion-pair intermediates in Sn2 substitutions has been obtained. ... 

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